Federal Opposition Leader Bill Shorten has declared the Labor Party needs new policy ideas and has outlined an ambitious goal to more than double its 44,000-strong membership.

Mr Shorten made the comments during a closed Labor policy forum in Melbourne yesterday, where he urged Labor to leave its days of disunity behind.

He warned that Labor could not win the 2016 election with the policies of 2013, and said once the party had settled on a new agenda all members must "lock in" behind it.

"When we arrive at a consensus, when we reach a policy position, we have an obligation to speak with one voice; shadow ministers, Caucus members, rank-and-file members, trade unions and party organisations alike," he said.

"I don't want the papers to be writing about our differences - I want them to be writing about our ideas and our policies."

The speech comes at a difficult time for the party, which is facing the prospect of losing government in both Tasmania and South Australia within a few weeks.

If that happened, the ACT's Chief Minister Katy Gallagher would be the highest Labor leader in office.